• Question: What are "slope efficiency" and "quantum defect"?

    Asked by michaelplease to Tianfu on 26 Jun 2012. This question was also asked by lauramorrisxx.
    • Photo: Tianfu Yao

      Tianfu Yao answered on 26 Jun 2012:

      Hi, in my research area we are aiming to get high optical output in terms of low used pump power. So we expect to design a fibre laser which is efficient. And the laser output power is linearly respected to absorbed pump power if the threshold has reached. Thus the slope between the absorbed pump power and the laser signal output is used and named as “slope efficiency”.

      The “quantum defect” corresponds to the slope efficiency, which is defined as the relative photon energy difference between pump and laser signal. According to the quantum theory, the photon energy relates with the optical wavelength. Since the normal signal photon has lower energy than the pump photon, the slope efficiency would >1. But we can try to close 1 by reducing the energy difference, which is the quantum defect.

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